Dear Sebastian,

We appologise for the delay in handling your manuscript soil-2015-91, submitted to SOIL, due to some technical errors and having to change editors.

The decision by the Topical Editor is: "reconsider after major revisions".

Please use the referee reports on SOIL Discussion and the Topical Editor comments below to revise your manuscript accordingly and then send back to us the revised manuscript and your responses to the referee and Technical Editor reports.

I am aware of the fact that you already posted responses to the referee reports on SOIL Discussion, so you can use these and add a response to the Technical Editor report.

Please make sure that it is clear in your response and on the revised manuscript where corrections were made. I advise to send one version of the manuscript with track changes and one clean version.

You can find below the Topical Editor's comments.

Kind regards,

Lily Pereg
Executive Editor, SOIL


Topical Editor's report:

Comments on “Tillage-induced short-term soil organic matter turnover and respiration” by S. R. Fiedler et al.

I agree with the comments of the two reviewers and in general also with the response of the authors. I would recommend major revisions of the manuscript before it might be considered for publication.

However, I have some further comments / suggestions for the revision of the manuscript:

I have similar problems as one of the reviewers with the statistical design of the study. The authors should be very clear that they used pseudo replicates. If I understood the paper correctly, the authors used just one experimental plot (6 x 30 m) and installed the three collars for CO2 measurements just in a distance of 1 m. This very small area was used to take the three soil samples too. This sampling strategy is not really representative for a field experiment also taking the spatial variability into account. The advantage of this strategy could be that small temporal changes might be detectable because of reducing the spatial variability.

The observed differences were mostly quite small and just of few of them were statistically significant (particularly differences observed in the relative proportions of compound classes - table 2). Therefore, I recommend to adapt the whole discussion section taking the limitations of the design and the rather small differences into account. The paper would really profit from shortening.

Some further comments:

Abstract:
Lines 19-20: I do not think that a higher proportion of volatilized matter during pyrolysis indicates an increased amount of SOM.
Line 26: the high spatial variability is based on a personal communication – very weak base. I wouldn’t use such an argument in the abstract.
Lines 27-28: increased in comparison to ???

Material and methods:
Lines 91-92: The content of organic C in the soil is much higher than the reported ones in table 1. This difference was not considered in the discussion. Are there any reasons for that?
I did not read any information about the history of the treatments. What kind of management has been applied before starting the experiment? Was the BD just once applied?
Lines 159-160: Please describe how samples were taken – composite samples of xy cores / subsamples??
Lines 175-176: I do not understand the implications / functions of the averaged survey spectrum per treatment. Does it mean that the proportions of compound classes were calculated based on one spectrum per treatment? How did you calculate means and standard deviations?
As one of the reviewers I did not understand the purpose of the hot water extraction.

Discussion
In the discussion I would prefer a more condensed way to discuss the most important findings of the study in a more straightforward way. I got the impression that OM in the digestate treatment was sometimes more and sometimes less available to microorganisms. That is not very consistent. The discussion from lines 350-365 is not convincing. I would think that OM from BD might enhance soil aggregation, resulting in less disruption of aggregates during tillage.
Line 381-385: I do not see that, i.e. an enrichment of (stable) SOM indicated by a higher portion of VM.

The discussion related to the rather small changes in hot water extractable N (and C) and relationships to Py-FIMS data is highly speculative and not very convincing. I would recommend to shorten this part substantially. I would strengthen the discussion related to relations between CO2 effluxes and changes in SOM composition (starting from line 438).
In the whole discussion about labile N I missed information about mineral N in the soil in the different treatments. This is the most available form of N.

Tables and figures
The standard deviations as indicated in table 1 are quite low. That might be the result of the design of the study and does not support the argument of high spatial variability.

Dear authors,
Thank you very much for the revision you did including the discussion of all of the reviewer´s comments. Your paper is almost ready for being accepted. I just have one minor comment which might be used to further improve your manuscript:
I am still not convinced by your argument that VM can be used as an indicator of SOM stability. Therefore I would suggest to remove the respective parts in the manuscript, i.e. line 386 “and also of its stability (Ludwig et al., 2015)” and the sentences from line 388 to 395.
Thank you again for the revision you did and for choosing SOIL!
Best regards,
Karsten

Thank you for your contribution to SOIL. We hope you consider SOIL in future publications!